Silicon Valley venture capitalist Guy Kawasaki launched his tech career at Apple as the company's "chief evangelist," marketing the original Macintosh computer.

During his time at Apple, Kawasaki worked closely with the late Steve Jobs, and says he learned a crucial lesson from the tech visionary.

Guy Kawasaki speaks at the Macworld 2010 conference.

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"One of the most important lessons that I learned from Steve Jobs is that changing your mind, changing what you're doing, reversing yourself at an extreme," Kawasaki told CNBC Make It at the Synergy Global Forum, "is a sign of intelligence."

"It's a sign of competence," he adds.

When Jobs first introduced the iPhone in 2007, it was a closed system — no one outside of Apple could create an app for it. Software developers had to use a Safari plugin to make their app work on the phone, as they weren't able to access the iPhone's system directly in order to ensure the phone's security.

Just one year later, however, Jobs made a complete "180-degree reversal," Kawasaki says. The founder opened the iPhone system to the public after realizing how much more the device could offer customers with apps written by anyone with a good idea.

The late Steve Jobs, Apple founder and former CEO, introduces the iPhone at a conference in 2007.

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"I learned the very valuable lesson that when you're doing something wrong, when you're doing something sub-optimally," he says, "it's a sign of intelligence to change your mind."

Kawasaki says this mindset — being able to admit a mistake and change — can help you get ahead in your career. It shows bravery and a commitment to success, he says.

"When you figure out you're doing something wrong, don't try to bluff your way, don't try to perpetuate a mistake," says Kawasaki, who is now chief evangelist at free graphic-design site Canva.